On my Macbook Pro running Mac OS X 10.8.2 (Mountain Lion) all the birthdays from the "Birthdays" calendar are showing a day early in Calendar. E.g. When I browse to contact Joe Bloggs in Contacts it shows his birthday as 12/03/1987. When I go into Calendar, there is a full day event for Joe Bloggs' birthday on 11/03/1987.

In Calendar I have selected the correct timezone (New Zealand Time) and have also enabled "Turn on time zone support" in the preferences. On my iPhone, I have the same settings and the birthdays display on the correct date.

Is there anything I can do to get the birthdays to display on the correct date in Calendar on my Macbook Pro?

Just out or curiousity, have you tried changing the date format in Contacts to mm/dd/yyyy? Maybe it's possible Calendar doesn't get the format. Just a quick, early morning thought.
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RichardNov 23 '12 at 11:29

This sould like you have scheduled a default reminder a day earlier. Have you checked the reminders (should be visible in the details of calendar entries).
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cyphoriousNov 23 '12 at 12:47

@Richard Still a day early, it understands the format just fine. All my other events are on the correct days.
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DanielGibbsNov 23 '12 at 19:04

@cyphorious Nope. It clearly puts the birthday event itself on the day before, not just a reminder.
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DanielGibbsNov 23 '12 at 19:05

I've added some conjecture since your discovery that it's only three months might move someone to figure the root cause out (or at least document how this is failing in a limited set of data).
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bmike♦Jun 9 '13 at 15:34

Actually it's worse than that. My contact cards are all incorrectly updated. So their contact cards are incorrect. They were entered years back correctly, but now they're incorrectly showing the day prior. For me it's inconsistent. This is the first place where I've found similar experiences and I know it's not consistently wrong, but I haven't got around to fully determining whether it's certain month specific only.
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user69370Feb 3 '14 at 10:09